Two houses ago, the second catastrophic plastic plumbing push fitting
failure (in our brand new build by Britain's favourite builder!) forced
us into a hotel while the builder lifted the floor (chipboard) on the
ground floor. I was allowed to take a peek and was shocked to see the
way that the floor was insulated:

From below, obviously, first the concrete (apparently with plenty of
polystyrene embedded). Then, on top, 2.5 cm fibre glass insulation (the
one with a paper sheet on one side, presumably to hold it together).
Then, ~50mm wooden battens (the ones with rubber strips underneath to
compensate for the uneaven concrete), and then the chipboard flooring on
top.

Now, the 50mm air gap between the insulation and the chipboard floor was
very well ventilated, so what the heck the purpose of the insulation
below was supposed to be was lost on me, in my view the floor should
have been insulated the way we do in Scandinavia, with the insulation
material in direct contact with the flooring, and with the air space
*below*. Anyway the site manager told me that this was the standard way
they insulate the ground floor so I just shook my head and let them get
on with it.

So now I'm in a third-floor flat by another builder, built around 2000,
and lo and behold what do I see when I cut open the chipboard floor to
move a radiator, exactly the same way of putting down the insulation. No
wonder the bloody floor is cold on your feet in the winter, through the
hole I can feel the draught and the insulation below the air gap would
be completely useless!

So, what possesses at least two British builders to lay floor insulation
in a way that is totally ineffective? Is this really according to
Building Standards?

On 22 Mar, 22:53, oh wrote:
Two houses ago, the second catastrophic plastic plumbing push fitting
failure (in our brand new build by Britain's favourite builder!) forced
us into a hotel while the builder lifted the floor (chipboard) on the
ground floor. I was allowed to take a peek and was shocked to see the
way that the floor was insulated:

From below, obviously, first the concrete (apparently with plenty of
polystyrene embedded). Then, on top, 2.5 cm fibre glass insulation (the
one with a paper sheet on one side, presumably to hold it together).
Then, ~50mm wooden battens (the ones with rubber strips underneath to
compensate for the uneaven concrete), and then the chipboard flooring on
top.

Now, the 50mm air gap between the insulation and the chipboard floor was
very well ventilated, so what the heck the purpose of the insulation
below was supposed to be was lost on me, in my view the floor should
have been insulated the way we do in Scandinavia, with the insulation
material in direct contact with the flooring, and with the air space
*below*. Anyway the site manager told me that this was the standard way
they insulate the ground floor so I just shook my head and let them get
on with it.

No responses yet - I guess nobody has seen this ?
How did you know it was paper-backed fibreglass without seeing both
sides of it ?
Was the void ventilated to outside ?
The rubber covered joists were on top of the fibreglass ? Or was it
just between the joists ?
If you description is correct, it seems rather odd. Who was the
builder ?

So now I'm in a third-floor flat by another builder, built around 2000,
and lo and behold what do I see when I cut open the chipboard floor to
move a radiator, exactly the same way of putting down the insulation. No
wonder the bloody floor is cold on your feet in the winter, through the
hole I can feel the draught and the insulation below the air gap would
be completely useless!

This is not a ground floor, I would be surprised if the void was open
to outside
ventilation.

So, what possesses at least two British builders to lay floor insulation
in a way that is totally ineffective? Is this really according to
Building Standards?

This all depends on whether the void was vented to outside or not.
Quite usual to batten concrete and boards on top.

Simon.

On Sat, 22 Mar 2008 22:53:10 +0000, a particular chimpanzee, oh
randomly hit the keyboard and produced:

Two houses ago, the second catastrophic plastic plumbing push fitting
failure (in our brand new build by Britain's favourite builder!) forced
us into a hotel while the builder lifted the floor (chipboard) on the
ground floor. I was allowed to take a peek and was shocked to see the
way that the floor was insulated:

From below, obviously, first the concrete (apparently with plenty of
polystyrene embedded). Then, on top, 2.5 cm fibre glass insulation (the
one with a paper sheet on one side, presumably to hold it together).
Then, ~50mm wooden battens (the ones with rubber strips underneath to
compensate for the uneaven concrete), and then the chipboard flooring on
top.

Now, the 50mm air gap between the insulation and the chipboard floor was
very well ventilated, so what the heck the purpose of the insulation
below was supposed to be was lost on me, in my view the floor should
have been insulated the way we do in Scandinavia, with the insulation
material in direct contact with the flooring, and with the air space
*below*. Anyway the site manager told me that this was the standard way
they insulate the ground floor so I just shook my head and let them get
on with it.

This isn't a normal flooring make-up. A concrete ground bearing slab
generally has a membrane and insulation underneath. When the client
wants a timber floor on top, one can place battens and boards over to
give the appearance of a timber floor, but it performs no other
function than being decorative. It shouldn't be ventilated, as it's
on the warm side of any insulation. In your case, I don't know why
there is additional insulation there.

So now I'm in a third-floor flat by another builder, built around 2000,
and lo and behold what do I see when I cut open the chipboard floor to
move a radiator, exactly the same way of putting down the insulation. No
wonder the bloody floor is cold on your feet in the winter, through the
hole I can feel the draught and the insulation below the air gap would
be completely useless!

There shouldn't be any deliberate ventilation between the joists in a
third-floor flat. And there should be substantially more than a bit
of insulation between the joists in a floor separating dwellings.

So, what possesses at least two British builders to lay floor insulation
in a way that is totally ineffective?

The housebuilding sector has the right to choose its inspectors,
rather like a burglar would have the right to choose who arrests him.
Hardened criminals, such as Barratts and Persimmons, frequently pick
the most lenient.

Is this really according to
Building Standards?

I suspect not, but as the NHBC is in the pocket of the major
housebuilders, who's going to say otherwise?
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed?"